Despite major advances in therapies, disparities in cancer and cardiometabolic outcomes continue to widen due to differences in socioeconomic status. Food and housing insecurity are social determinants of health that are associated with morbidity from obesity, diabetes, cardiovascular disease, and psychological stress, and food insecurity contributes to income disparities in cancer mortality. Although the associations between social needs and health are well-defined, there is a research gap as to whether policies or programs to address food and housing insecurity, particularly through health systems, improve diet, obesity, health, and healthcare utilization. Some states are experimenting with Accountable Care Organizations (ACOs) in their Medicaid programs with the goal of incentivizing providers and organizations to deliver higher value care, and some ACOs are starting to address social needs. In January 2020, the state of Massachusetts will, for the first time, provide funding directly to Medicaid ACOs to address food and housing needs through the Delivery System Reform Incentive Payment Flexible Services program. Implementation of this program is a natural experiment that could provide important knowledge about the impact of state-level funding for food and housing needs on diet and health outcomes. The main objectives of this study are to evaluate how the Flexible Services program affects the dietary quality, psychological stress, health, and health care utilization of adult ACO participants and to assess program implementation. The project will take place at five community health centers (CHCs) affiliated with Partners HealthCare, a large health care organization that has contracted with the state as a Medicaid ACO. The project is time-sensitive because the pre-program implementation assessment of diet, stress, food/housing insecurity, and access to resources must be completed before program implementation in 2020. A total of 800 Medicaid ACO patients (Med-ACO) and 200 non-Medicaid CHC patients with food/housing insecurity (Control) will be enrolled and followed for 4 years. Survey, 24-hour dietary recall (ASA24), electronic health record (EHR), and claims data will be collected. Primary outcomes will be change in dietary quality, stress, and food/housing insecurity (Aim 1) and change in body mass index, blood pressure, and acute health care utilization (emergency department visits; hospitalizations) (Aim 2) comparing: a) Med-ACO participants who screen positive for food/housing insecurity pre-implementation vs. Control, and b) Med-ACO participants who screen positive for food/housing and receive Flexible Services (exposed) vs. Med-ACO participants who screen positive but do not receive Flexible Services (not exposed). Aim 3 will assess implementation factors that influence the effectiveness of the program, guided by the RE-AIM/PRISM framework. Results will inform policymakers and researchers about the effectiveness of a novel state-level program for delivering food and housing resources through Medicaid ACOs and will help refine ongoing and future state and community programs that will reduce income disparities in cancer and cardiometabolic disease.